Research background related to this disclosure is outlined in the following:
1. 3D Printing and Appearance Fabrication
Among numerous 3D printing technologies, many methods are included for fabricating models having desired physical attributes, such as for obtaining desired stress distribution (Stava, O., Vanek, J., Benes, B., Carr, N., Mech, R. 2012. Stress relief: Improving structural strength of 3d printable objects. ACM Trans. Graph. 31, 4, 48.), articulated models (Bacher, M., Bickel, B., James, D. L., Pfister, H. 2012. Fabricating articulated characters from skinned meshes. ACM Trans. Graph. 31, 4, 47; Cali, J., Calian, D. A., Amati, C., Kleinberger, R., Steed, A., Kautz, J., Weyrich, T. 2012. 3d-printing of non-assembly, articulated models. ACM Trans. Graph. 31, 6, 130.), model balance (Prevost, R., Whiting, E., Lefebver, S., Sorkine-Hornung, O. 2013. Make it stand: balancing shapes for 3d fabrication. ACM Trans. Graph. 32, 4, 81.), movable models (Coros, S., Thomaszewski, B., Noris, G., Sueda, S., Forberg, M., Sumner, R. W., Matusik, W., Bickel, B. 2013. Computational design of mechanical characters. ACM Trans. Graph. 793 32; Ceylan, D., Li, W., Mitra, N. J., Agrawala, M., Pauly, M. 2013. Designing and fabricating mechanical automata from mocap sequences. ACM Trans. Graph. 32, 6, 186; Thomaszewski, B., Coros, S., Gauge, D., Megaro, V., Grinspun, E., Gross, M. 2014. Computational design of linkage based characters. ACM Trans. Graph. 33, 4 (July), 64:1-64:9.), and deformable objects, etc. (Bickel, B., Bacher, M., Otaduy, M. A., Matusik, W., Pfister, H., Gross, M. 2009. Capture and modeling of non-linear heterogeneous soft tissue. ACM Trans. Graph. 28, 3 (July); Skouras, M., Thomaszewski, B., Coros, S., Bickel, B., Gross, M. 2013. Computational design of actuated deformable characters. ACM Trans. Graph. 32, 4, 82.). Yet, none of these methods considers surface color of the object.
There are other methods for creating desired appearance attributes, such as surface reflectance (Weyrich, T., Perrs, P., Matusik, W., Rusinkiewicz, S. 2009. Fabricating microgeometry for custom surface reflectance. ACM Trans. Graph. 28, 3, 32; Matusik, W., Ajdin, B., Gu, J., Lawrence, J., Lensch, H. P. A., Pellacini, F., Rusinkiewicz, S. 2009. Printing spatially varying reflectance. ACM Trans. Graph. 28, 5, 128; Lan, Y., Dong, Y., Pellacini, F., Tong, X. 2013. Bi-scale appearance fabrication. ACM Trans. Graph. 32, 4, 145.), subsurface scattering (Dong, Y., Wang, J., Pellacini, F., Tong, X., Guo, B. 2010. Fabricating spatially-varying subsurface scattering. ACM Trans. Graph. 29, 3, 62; Hasan, M., Fuchs, M., Matusik, W., Pfister, H., Rusinkiewicz, S. 2010. Physical reproduction of materials with specified subsurface scattering. ACM Trans. Graph. 29, 3.), and for realizing desired reflectance functions (Malzbender, T., Samadani, R., Scher, S., Crume, A., Dunn, D., Davis, J. 2012. Printing reflectance functions. ACM Trans. Graph. 31, 3, 20.). These methods produces desired appearance by modifying microscopic geometric details of the materials, and are limited to certain types of materials. Instead, the method of this disclosure is intended for accurately coloring 3D object surface according to user-specified texture without modifying the object itself, and is applicable for a wider range of material types.
2. 3D Object Surface Coloring Technologies
Existing technologies for coloring 3D object surface have their own merits and limitations. 3D color printers offer high quality coloring for curved surface, but supporting only limited selection of colors and materials, and incurring very high costs. Vinyl decals can print patterns of arbitrary colors onto object surfaces, but are only applicable to simple geometries. Electrical plating and enameling require sophisticated devices, and are only applicable to limited types of materials, such as metal and ceramics, incurring relatively high costs. Water transfer printing supports both complex textures and various material types, including metal, plastic, and woods, and has been extensively used to decorate furniture, electronic products, and automotive accessories. Yet, there is no method to-date for simulating the water transfer printing process. Thus, the traditional water transfer printing does not support accurately controllable printing process. These limitations have confined existing water transfer printing process to reproducing repeated patterns that do not require very accurate positioning.
3. Viscous Sheet Simulation
The presently disclosed calculable water transfer printing technology performs the simulated calculation by approximating a PVA film with a thin viscous sheet. The thin viscous sheet dynamics model is built on the foundation of continuum mechanics (Ribe, N. 2002. A general theory for the dynamics of thin viscous sheets. Journal of Fluid Mechanics 457, 255-283; Batty, C., Uribe, A., Audoly, B., Grinspun, E. 2012. Discrete viscous sheets. ACM Trans. Graph. 31, 4 (July).). Other than the thin viscous sheet kinematic model, the simulated calculation of this disclosure further involves Stokes flow (White, F. M., Corfield, I. 1991. Viscous fluid flow, vol. 3. McGraw-Hill New York.) as an approximation of the Navier-Stokes equation in the regime of low Reynolds numbers. In this disclosure, these models have been simplified to a two-dimension process in order to offer fast and accurate simulation for the dynamics of the thin sheet.
4. Texture Mapping
Texture mapping is widely used in coloring 3D models in the virtual regime. Numerous algorithms may be leveraged to calculate a mapping relationship between a 3D model surface and a planar pattern with minimum angle and/or area distortion (Sander, P. V., Snyder, J., Gortler, S. J., Hoppe, H. 2001. Texture mapping progressive meshes. In Proceedings of SIGGRAPH'01, ACM, New York, N.Y., USA, 409-416; Levy, B., Petitjean, S., Ray, N., Maillot, J. 2002. Least squares conformal maps for automatic texture atlas generation. ACM Trans. Graph. 21, 3, 362-371; Desbrun, M., Meyer, M., Alliez, P. 2002. Intrinsic parameterizations of surface meshes. Comput. Graph. Forum 21.) while satisfying user-specified feature corresponding relationship (Kraevoy, V., Sheffer, A., Gotsman, C. 2003. Matchmaker: constructing constrained texture maps. ACM Trans. Graph. 22, 3, 326-3338; Zhou, K., Wang, X., Tong, Y., Desbrun, M., Guo, B., Shum, H.-Y. 2005. Texturemontage: Seamless texturing of arbitrary surfaces from multiple images. ACM Trans. Graph. 24, 3.). Unlike the texture mapping which colors virtual models, the presently disclosed method colors real-world 3D objects.